LIGO Hanford Observatory News

- Contributed by Fred Raab

Building and operating a gravitational-wave detector requires
a broad spectrum of skills, and the resident staff at LIGO Hanford
Observatory is a pretty diverse group of people. Some are Ph.D.
physicists who have expertise from various experiments. Some are
senior engineers, who have designed, built or worked on major
high-tech facilities like a particle accelerator or radio astronomy
observatory. Some got their high-tech background working on projects
with the U.S. Navy, either in service or as a contractor. Some are
recent college graduates. Areas of staff expertise include physics,
geophysics, civil engineering, electrical and electronics engineering,
mechanical engineering, software engineering and vacuum engineering.
Because of the newness of this field, very few people have experience
with precision laser interferometers. And absolutely no one has
experience with kilometer sized interferometers, because LIGO's 2-km
interferometer at Hanford will be the first of its kind!

Ever since work began toward using laser interferometers to detect
gravitational waves in the early 1970's, the U.S. effort has been
centered around test interferometers operated by small groups of Ph.D.
physicists and graduate students at Caltech and MIT. Over the past decade,
there have been typically only about a dozen people in the U.S. who could
be "left alone" to operate one of these gravitational-wave detector test
beds. The challenge now is to come up with about two dozen people at both
of the Hanford and Livingston observatories, who can run, diagnose and fix
interferometers and manage the online data analysis.

How do you quadruple the knowledgeable population of interferometer
experts in a few short years? One aspect of a solution has been to
design and build equipment with more of a "turn-key" nature than the
campus test beds, which were designed to be operated by the designers.
The second is to find people with a range of skills and backgrounds,
lots of enthusiasm, a sense of adventure, and then fill in whatever
else is needed to make them experts in this new field. At Hanford we
have been able to attract people with the requisite qualities early,
and to have them work with the designers to install and commission
hardware. Now that people have developed a visual memory of the
hardware, and knowledge of the practical aspects of the instrumentation,
the time is ripe for a systematic education in interferometer science
and engineering.

The first step in that education is LIGO Basic Training, a series of
lectures aimed at developing a common set of conceptual tools for
understanding the science of LIGO. Topics will include Basic Calculus,
Spectral Analysis, Statistics, Basic Electronics, Vacuum Practice,
Mechanics, Geophysics, Thermodynamics, Optics, Quantum Mechanics,
Special Relativity, General Relativity and Astronomy. The emphasis of
LIGO Basic Training is on concepts rather than details. For instance,
visualizing a partial derivative counts for more than being adept at
calculating it, since a computer would likely do the calculation in
daily operations if needed. A second course of lectures, to be entitled
The Physics of LIGO, will follow up later with a much deeper treatment
of interferometer issues. This course will be derived from a course
of similar name organized a few years ago at Caltech by Professor Kip Thorne,
in which LIGO scientists and graduate students presented lectures to their
faculty and student colleagues.

So far LIGO Basic Training has had four of the weekly lectures, presented by
Fred Raab, covering calculus, Fourier transforms, transfer functions, power
spectrum estimation and probability distributions. In Figure 1 at left above,
Fred is trying to help people visualize vector fields that have non zero curl
or divergence. And in Figure 2 at right, vacuum engineer Kyle Ryan asks a question
to try to nail down this picture. Sometimes it helps to go outside the lecture
format to pin down understanding of a new concept. Scientist Rick Savage
recently demonstrated a number of aspects of working in frequency space, using
a signal analyzer to measure thermal noise from a resistor and to identify the
presence of a coherent signal added to this noise. Pretty soon the first
projects will be assigned to make a "hands-on" connection to the concepts
developed in class.